REINFORCING IMPACT BEAM AND A WALL PORTION OF A VEHICLE HAVING AT LEAST ONE IMPACT BEAM

Abstract: Impact beam for reinforcing a wall portion of a motor vehicle is provided as a profile made of light metal or light metal alloy. The profile applied as the impact beam in the wall portion comprises two wall elements extending substantially parallel to a principal plane of the wall portion and spaced from each other orthogonally to the principal plane, and at least two connecting webs linking these wall elements and spaced from each other in a direction parallel to the principal plane. The connecting webs are linked, in a central region between the two wall elements, by at least and preferably one intermediate wall substantially parallel to the wall elements so as to enhance its inclination resistance and to improve its impact absorption behaviour.

Description: REINFORCING IMPACT BEAM AND A WALL PORTION OF A VEHICLE HAVING AT LEAST ONE IMPACT BEAM. The present invention relates to an impact beam for reinforcing a wall portion of a motor vehicle, in -particular a side wall portion or a door of a passenger car, this impact beam being a profile made of light metal or light metal alloy applied as a component of the wall portion having two wall elements substanti¬ ally parallel to a principal plane of the wall portion and spaced from each other orthogonally to the principal plane, as well as at least two connecting webs linking these wall elements, spaced from each other in a direction parallel to the principal plane. Such an impact beam is known, for instance, from European Patent No. 0 235 091 Bl. The impact beams concerned are incorporated in the respective wall element in such a way that they restrict deformation of this wall element in case of an impact against the respective wall element, in particular by another vehicle driving towards the respective wall element in the orthogonal direction, so as to protect persons and/or objects positioned behind this wall element. Here, these wall elements are to behave in such a way that they absorb as much of the impact energy as possible on a deformation path perpendicular to the principal plane of the wall element. The decisive factor thus is that the wall element and in particular the impact beam used for reinforcing offers a relatively great impact resistance, not only when the impact action begins, but also during the subsequent deformation, in spite of the respective deformation that has already taken place. It is an object of the present invention to provide an impact beam of the above type having minimum weight and offering an even more favourable deformation behaviour with as high deformation strength as possible complying with the requirements indicated above. In order to solve this problem an impact beam according to the present invention is provided with connecting webs interconnected in a central region between the two wall elements by at least, and preferably one, intermediate wall substantially parallel to the wall elements. It was proved that, with the beam design according to the invention, the impact behaviour of the impact beam, and a wall portion provided therewith can be further improved at constant weight per unit length or, in other words, that for a certain impact behaviour required by car manufacturers and safety regulations, the weight per unit length of the impact beam may be reduced. In particular, it has turned out that the energy absorption properties of the wall portion and the impact beam, respectively, are improved by maintaining the cross-section of the beam even at severe deformation. The deformation strength of the impact beam substantially depends on dimensions of the wall elements connected to each other and supported against each other by connecting webs, and furthermore on the distance therebetween. Here, the wall thickness and the length of the connecting webs also influence the stability of the impact beam and thus the deformation behaviour. The distance between the wall elements cannot be reduced, as reducing this distance would inevitably lead to a decrease in the deformation strength of the impact beam as a whole. It is, however, possible to reduce the wall thickness of the connecting webs by integrat¬ ing the intermediate wall. Further improvement of the deformation strength of the impact beam may be achieved by forming the connecting webs curved or inclinating towards the intermediate wall. The degree of inclination is critical here. Decrease in the proximity of the connecting webs resulting from the curving or inclination should be within a range corresponding to from approximately 1.0 times to approximately 6.0 times the wall thickness of the connecting webs. Preferably the proximity decrease corresponds to at least 2.0 times and most preferred to at least 3.0 times the wall thickness of the connecting webs. The resulting divergence of the connecting web portions from the intermediate wall is to be relatively small, so that controlled deformation behaviour of the impact beam is achieved. Too great a divergence of connecting web portions opposing each other would have adverse effects on the stability of the impact beam. A further advantage may be achieved by linking the connecting webs to the intermediate wall in the impact beam, where the full height of the impact beam throughout the whole length may not be employed for reasons of space. In such cases, one of the chambers of the impact beam may be prefolded locally in a controlled fashion without weakening the connecting webs in the chamber not folded. Preferably the intermediate wall is situated in a region of closest proximity of the connecting webs and in particular in the geometric center between the two wall elements. The profile may be formed substantially symmetrically with respect to the center plane of the intermediate wall, but this is not necessary. It may turn out to be advantageous to depart from this symmetry in view of the fact that in case of an impact, the outer wall element is substantially subjected to pressure, while the profile region adjacent to the other wall element facing the interior space is substantially subjected to tension load, so that for optimization it might be advantageous to depart from this symmetry. According to a preferred embodiment the connecting webs run substantially linear and diverging from the intermediate wall towards at least one wall element. Here, according to a first embodiment it is conceivable for the connecting webs to run substantially linear and diverging from the intermediate wall to both wall elements, optionally at different divergence angles. But it is also conceivable for the connecting webs to run substantially linear and diverging towards one of the wall elements only, while, on the other hand, the connecting webs run substantially linear and at constant distance or smaller divergence from the intermediate wall to the other wall element. Furthermore, it has turned out that optimization of the bending and energy absorption behaviour at impact load, providing for as little weight per unit length of the impact beam as possible, is achieved if the mutual distance between the connecting webs is at least 40%, preferably at least 50%, most preferably at least 60% and preferably less than 100% of the distance between the wall elements, the distances each time being measured between the center planes of the connecting webs and the center planes of the wall elements and the transition curvatures not being taken into account in these measures; in case of inclinating or curved connecting webs their distance is to be measured in the region of closest proximity. It is conceivable that at least one of the wall elements protrudes beyond at least one of the connecting web faces facing away from each other. In case of a profile shape wherein the connecting webs, departing from the intermediate wall, converge more strongly to a first wall element than to a second wall element, it may be sufficient if only this second wall element protrudes beyond the faces of both connecting webs facing away from each other. In principle it is also possible for both wall elements to protrude beyond those faces of both connecting webs facing away from each other. It is also conceivable that the wall thickness of the connecting webs from the intermediate wall to a first wall element is greater than the wall thickness of the connecting webs from the intermediate wall towards a second wall element, in particular if the first wall element preferably is the inner wall element, as seen from the interior of the vehicle. This configuration again takes into account the different load and deformation behaviour in the profile region near the interior space and that remote from the interior space. It is also conceivable to provide several, preferably at least two pairs of connecting webs inclinating or curved towards each other, with one intermediate wall each, between the wall elements. In this case, the protrusion of the wall portions is automatically formed between the pairs of the connecting webs. Moreover, it is also possible for the wall elements to protrude beyond the webs at the ends as well, so that the deformation of the wall elements along their total height may be kept under control to as far an extent as possible. With an embodiment where several pairs of connecting webs are provided it has turned out to be favourable in view of the above requirements that the distance between the adjacent connecting webs of adjacent pairs of connecting webs is greater than the distance between the respective connecting webs constituting one pair. The profile may be produced by metal extrusion, preferably from aluminum or aluminum alloy. The wall portion having an impact beam of the above configuration is also a subject matter according to the present invention. The accompanying drawings, Figs. 1-9, illustrate the invention by way of exemplary embodiments, where Fig. 1 shows in a schematic inside view a motor vehicle door provided with an impact beam according to the invention; Fig. 2 is a schematic section of the door taken along line II-II of Fig. 1, and Figs. 3-9 illustrate various embodiments of impact beams according to the invention. In Fig. 1 a motor vehicle door is generally depicted as 10 displaying the frame 12 of the door. In the region of a cut-away portion 16 of the inner wall of the door or cover panel, an impact beam 18 according to the invention which is attached to the frame 12 at 20 and 22 with possibility to reduce the width of the impact beam 18 in the end regions E as viewed orthogonally to the door plane, so that the door thickness as measured orthogon¬ ally to the plane of projection may be kept small in spite of attachment to the door frame 12 in these end regions as well. This configuration does not substantially impair the deformation behaviour of the impact beam, as it is the central longitudinal region M which is substantially responsible for the deformation behaviour. Fig. 2 shows the orientation of the profile of the impact beam 18 between the outer wall 24 of the door and an interior cover panel 26. The principal plane of the door is depicted as H-H. This principal plane is drawn in each of the following Figs. 3-9 so as to always be aware of the orientation of the impact beam with respect to the principal plane H. In Fig. 3 the impact beam 18 consists of a wall element 30 and a wall element 32. The two wall elements 30 and 32 are intercon¬ nected to each other by means of a connecting web 34 and a connecting web 36. The connecting webs 34 and 36 are inclinated towards each other, so that they have a minimum distance a m i j in a central region MB and a distance a max at the junctions 38 with the wall elements 30 and 32. In the central region the two connecting webs 34 and 36 are linked to each other by an intermediate wall 40. The distance b between the wall elements 30 and 32 is measured between center planes m 30 and m 32 , while the distances a max and a m n of the connecting webs are measured between the center planes m 34 and m 36 . The wall elements 30,32 extend beyond the connecting webs 34 and 36 forming projections designated by u. The impact beam is formed symmetrically with respect to a plane of symmetry S-S. The wall thickness of the connecting webs is designated by d. In the embodiment of Fig. 4, similar parts are depicted by the same reference numerals as in Fig. 3, always augmented by the number 100. The substantial difference between the embodiment of Figs. 4 and 3 resides in the fact that web portions 134 a and 136 a adjacent to the wall element 130, which is the outer one with respect to the interior of the vehicle, have a small thickness d a than the sections 134k and 136^ adjacent to the in this case interior wall element 132, the thickness of which is depicted by d-^. In the embodiment of Fig. 5, similar parts are again designated by the same reference numerals as in Fig. 3, always augmented by the number 200. This embodiment is different from those of Figs. 3 and 4 in that the projections u are not incorporated. In the embodiment of Fig. 6 similar parts are designated by the same reference numerals as in Fig. 3, always augmented by the number 300. Fig. 6 is different from the embodiment of Fig. 3 in that, departing from the intermediate wall 340, only the web portions 334 ]; - and 336^ diverge towards the wall element 332 being the inner one with respect to the interior of the vehicle, while the web portions 334 a and 336 a run substantially parallel to each other or diverge to a lesser extent than the web portions 334 ]; ,, 336 } -,. With this embodiment the projections u are only provided at wall element 330, preferably being installed as the outer wall element, i.e. that facing away from the interior of the car. In the embodiment of Fig. 7, two pairs of connecting webs 434 and 436 are provided between the two wall elements 430 and 432, having one intermediate wall 440 each. The distance c between the adjacent connecting webs 434 and 436 of both pairs is greater than the distance a max between two connecting webs 434 and 436 belonging to a common pair. Here the projections u are provided on both wall elements 430 and 432. Returning to Fig. 3, it has to be said that the difference a max a min - 3 somewhat smaller than width b and amounts to about 60% c the width b. Fig. 3 shows transition curvatures R lf R 2 ,R 3 . These transition curvatures are of importance; their radius of curvature is determined by calculation or simple pretests. It is to be noted that the connecting webs of Fig. 7 may have the same configuration as shown in Fig. 4. Furthermore, it is to be noted that the projections u of Fig. 7 may be omitted on at least one of the wall elements, as shown in Figs. 5 and 6. A particular advantage of the solution according to the present invention in terms of reducing the weight while maintaining the impact characteristics resides in the fact that, due to the intermediate wall 40 between the connecting webs 34,36, the wall thickness of these connecting webs may be kept relatively small without losing the spacing function of these connecting webs. This can be seen in Fig. 3, where the wall thickness of the connecting webs is chosen to be considerably smaller than the wall thickness of connecting webs and wall elements are substan¬ tially the same. Here the wall thickness of intermediate wall 40 may be relatively small; it may be approximately equal to the wall thickness of the connecting webs 34,36. Thus, in spite of the shape of the connecting webs, which appears to be unfavour¬ able at first sight because of the inclination and as such might jeopardize the spacing function of the connecting webs, an altogether positive result may be obtained by the simultaneous application of the intermediate wall, which is surprising. The combination of connecting webs brought closer to each other and the intermediate wall ensures not only reinforcing, but also controlled deformation of the impact beam in case of a crash. Fig. 8 shows an embodiment which differs from that of Fig. 3 only in that the webs 534 and 536 are not inclinating towards each other but extend substantially linear. The embodiment of Fig. 9 differs from that of Fig. 8 in that folds 635 are introduced into the web portions 634a by controlled deformation (prefolding) . These folds are preferably introduced by controlled deformation prior to installation into the door or the wall portion. These folds 635 may, but need not, extend throughout the total length of the impact beam 618. It is conceivable to provide these folds 635 only over a part of the length of the impact beam 618, e.g. at the beam ends, and le them continuously level out until they disappear. In this way a impact beam is obtained whose width b^ in a region of longi tudinal extension is smaller than width b 2 in a different regio of longitudinal extension. Here it is also conceivable for th impact beam 618 to have the full width b 2 over a part of it length and to have the reduced width b^ over a smaller or large remaining part of its length by the simple fact that the fold 635 extend only over this remaining part of the length. In this way it is possible to obtain an -impact beam that may b used if there is room for the full width b 2 only over a certai region inside the door or a wall portion. Here these two we portions 634b remain non-deformed and are still fully availabl to provide sufficient deformation strength, their support bein provided for by intermediate wall 640.

Claims: laims 1. An impact beam (18) for reinforcing of a wall portion (10) of a motor vehicle, in particular a side wall portion or a door (10) of a passenger car, the impact beam (18) being a profile made of light metal or light metal alloy comprising two wall elements (30,32) extending substantially parallel to a principal plane (H-H) of the wall portion and spaced from each other orthogonally to the principal plane (H-H) , as well as at least two connecting webs (34,3-6) interconnecting these wall elements (30,32), spaced from each other in a direction parallel to the principal plane (H-H) , c h a r a c t e r i z e d i n that the connecting webs (34,36) are interconnected to each other in a central region (MB) between the two wall elements (30,32) by at least and preferably one inter¬ mediate wall (40) extending substantially parallel to the wall elements (30,32). 2. The impact beam according to claim 1, c h a r a c t e r i z e d i n that the connecting webs (34,36) are inclinated or curved towards each other. 3. The impact beam according to claim 2, c h a r a c t e r i z e d i n that the intermediate wall (40) is situated in a region (MB) of closest proximity of the connecting webs (34,36). 4. The impact beam according to any of claims 2 or 3, c h a r a c t e r i z e d i n that the proximity (a max - a m i n ) of the connecting webs (34,36) caused by inclination or curving amounts to from about 1.0 times to about 6.0 times the wall thickness (d) of the connecting webs (34,36). 5. The impact beam according to any of claims 1 to 4, c h a r a c t e r i z e d i n that the profile is formed substantially symmetrically with respect to a center plane of the intermediate wall (40). 6. The impact beam according to any of claims 1 to 4, c h a r a c t e r i z e d i n that the profile is formed asymmetrically with respect to a center plane of the intermediate wall (40) . 7. The impact beam according to any of claims 1 to 6, c h a r a c t e r i z e d i n that the connecting webs (34,36) run substantially linear and diverging from the intermediate wall (40) towards at least one wall element (30,32). 8. The impact beam according to claim 7, c h a r a c t e r i z e d i n that the connecting webs (34,36) run substantially linear and diverging from the intermediate wall (40) to both wall elements (30,32). 9. The impact beam according to claim 7, c h a r a c t e r i z e d i n that the connecting webs (334 a ,336 a ) run substantially linear and at constant distance or smaller divergence from the intermediate wall (340) to the other wall element (330) . 10. The impact beam according to any of claims 1 to 9, c h a r a c t e r i z e d i n that the mutual distance between the connecting webs (34,36) is at least 40%, preferably at least 50%, most prefer¬ ably at least 60% and preferably less than 100% of the distance (b) between the wall elements (30,32), the distances (a,b) each time being measured between the center planes (m 3 4,m 3 g) of the connecting webs (34,36) and the center planes (m 3 o,m 3 ) of the wall elements (30,32) and the transition curvatures (R lf R 2 ,R 3 ) not being taken into account in these measures, and the distance (a) being measured in the region of closest proximity of the connecting webs (34,36) in case the connecting (34,36) are inclinating or curved. 11. The impact beam according to claim 10, c h a r a c t e r i z e d i n that where the connecting webs (334^,336^), departing from the intermediate wall (340) , diverge more strongly towards a first wall element (332) than towards a second wall element (330) , the second wall element (330) extends beyond the connecting webs (334 a ,336 a ) facing away from each other. 12. The impact beam according to any of claims 1-11, c h a r a c t e r i z e d i n that the wall thickness (d^) of the connecting webs (134j D ,136 jD ) from the intermediate wall (140) to a first wall element (132) is greater than the wall thickness (d a ) of the connecting webs (134 a ,136 a ) from the intermediate wall (140) to the second wall element (130) . 13. The impact beam according to claims 1 to 10, c h a r a c t e r i z e d i n that several, preferably at least two pairs (434,436) of connecting webs (434,436) optionally inclinating or curved towards each other are provided between the wall elements (430,432) with one intermediate wall (440) each. 14. The impact beam according to claim 12, c h a r a c t e r i z e d i n that the distance (c) between the adjacent connecting webs (434,436) of adjacent pairs of connecting webs (434,436) is greater than the distance (a) between the respective intermediate webs (434,436) constituting one pair. 15. The impact beam according to any of claims 1 to 14, c h a r a c t e r i z e d i n that two webs (634a) opposing each other are prefolded by controlled deformation at least over a part of the longitudinal extension of the impact beam (618) . 16. A wall portion of a motor vehicle, in particular a side wall portion or door of a passenger car, having at least one impact beam according to any of claims 1 to 15.

Inventors: CLAUSEN EDVIN LIST, GAERTNER JOST, CLAUSEN, EDVIN, LIST, GAERTNER, JOST
Applicants: CLAUSEN EDVIN LIST, GAERTNER JOST, NORSK HYDRO AS, CLAUSEN, EDVIN, LIST, GAERTNER, JOST, NORSK HYDRO A.S.
Application year: 1994
Main classification: B60J5
IPC codes: B60J5, B60R19, B62D21, B62D25